- Signal degradation
- Video flicker
- Video distortion
Surprisingly, we have also seen this issue connected to gas lift office chairs. When people stand or sit on gas lift chairs, they can generate an EMI spike which is picked up on the video cables, causing a loss of sync. If you have users complaining about displays randomly flickering it could actually be connected to people sitting on gas lift chairs. Again swapping video cables, especially for ones with magnetic ferrite ring on the cable, can eliminate this problem. There is even a white paper about this issue.
Issues such as those mentioned above are particularly evident in video cable converters.
If you are using a DisplayPort to HDMI, DisplayPort to DVI, DisplayPort to VGA or HDMI to VGA cable and are having issues we recommend using an active video adapter in conjunction with a video cable as illustrated below:
DisplayPort output > DisplayPort to HDMI active adapter > HDMI to HDMI cable > Monitor input
DisplayPort output > DisplayPort to DVI active adapter > DVI to DVI cable > Monitor input
DisplayPort output > DisplayPort to VGA active adapter > VGA to VGA cable > Monitor input
HDMI output > HDMI to VGA active adapter > VGA to VGA cable > Monitor input
What is the difference between active and passive?Active cables and adapters contain have their own built in chip which converts the video signal from say DisplayPort to HDMI, they also convert the digital DisplayPort or HDMI signal to the analogue VGA signal
Passive cables and adapters do not have such a conversion chip built in. Instead they rely on the source to do the conversion. Unless the source has the ability to output analogue over DisplayPort or HDMI then an active adapter is required for VGA output.
What active adapters do you recommend?We cannot recommend one over another but we do regularly use the following in our test lab:
DisplayPort to HDMI adapter:
DisplayPort to DVI
DisplayPort to VGA
HDMI to VGA
Please be aware that DisplayPort adapters will only work in one orientation with the DisplayPort being connected to the source output and not the input on a monitor
Similarly HDMI to VGA adapters will only work with HDMI as being connected to the source output and not the input on a monitor